jetting @ 4000ft

[Liege]

Hi there,

I have an '01 KDX200. I have idle issues with the bike. THe idle screw is all the way in, air screw can be anywhere from 1 to 2 or even 3 turns out and makes no difference to idle speed. I opened up the carb and it has needle R1174K centre clip position with main jet #160 slow jet is #60. It has an FMF knarley with powercore II on.

When running anywhere above 1/4 throttle it has great power, but it struggles to idle and there is no hit off the bottom.

Normal altitude is around 1400m (4200ft) temperature is 18-28'C

I know this jetting is way off what everyone else is saying but thats how I got it? I run 40:1 motul syn oil.

THe bike is quite heavy on fuel and has quite a bit of spooge. I repacked the silencer a month ago. I have no problems with plugs fouling.

Suggestions? Could it be compression related? Where do I start? Thanks

 

[dirt bike dave]

Start with jetting.

It's been a long time since I had a 200, but your jetting seems way too rich to me for that altitude, espeically on the slow jet.

I think you will end up one or two sizes down on the main (158 or 155), with a bigger change on the slow speed jet. Can't remember what needle works best, but that is another area. You will be much happier with the bike when you get the jetting cleaned up.

 

[John Harris]

From this distance and without doing a lot of other checking, my suggestion is jetting, jetting, jetting. Start by putting your needle clip in the next to top position. Then change your pilot jet to 40 to 42 to get in the real world. Try this out and then work on the main. Bike is loading up with fuel because of the ultra rich pilot (air screw position does not make any difference). When you open throttle, engine literally has to clean out fuel surplus before it can begin to rev and power correctly. Just guessing, but at 4000 ft I suspect you will end up around 40 and 152 on jetting. Cheers John

 

[jschiller]

Liege, you are deffinately running too rich, either take the bike to RCR for jetting or mail them and ask for the standard settings they recomend, remember to mention all the mods on your scoot
Cheers Joe :ride:

 

[Liege]

CORRECTION pilot jet is #48

My sincere apologies, I checked out the jets again last night just to be sure and found that the pilot is a #48 not a #60 as I mentioned earlier. I got confused with the main being a #160.

Where to start?

Sorry and Thanks.

Joe I agree RCR racing will prob be able to sort it out, but they are on the other side of town and its a mission getting the bike to them. I think I will phone up Russel directly and chat to him about it as well but its good to find out what the guys on this forum say before doing that.

 

[jsirvine]

I'm at 4250' and am running 40-1 with a 145 main, no airbox lid and a PC pipe. Can't remember what the pilot is or the clip as I have been set this way for a few years now. Originally I had lots of fouling issues but now I can run a plug forever and have good power and smoothness throughout.

 

[matt-itude]

I run a 38 pilot and 148 main @ 4500 and above. used to have idle problems until I got my pilot jet sized right. I have a woods pipe and vforce3s. I believe the vforce will leave me a size or two smaller on the pilot than you and one size on the main plus I ride typically a 1000 higher than your stated elevation. (I think John Harris is probably within 1 size on his recomendations if not right on the money).

 

[thebuilderdude]

I have the same bike and set up. I use stock jetting and run 40:1 to 44:1 synthetic oil. I also ride anywhere from 1500 feet to 6000 feet. Never foul plugs and never have power issues. Have great even power all the way through. I’ve been running the same plug for years. When I first got the gnarly, the guys at the bike shop told me it was a must to jet it up. Put in a bigger pilot and main and found out that it just fouled plugs all day long. Remember woods bikes typically aren't running wide open throttle for very long, or ever in my case. So I feel the larger jetting is unnecessary. Also if your idle speed screw is turned to far in your air screw will not be as affective. Start with stock jetting especially on the pilot.